Losses (including loss of cargo and pollution) resulting from accidents occurring in a body of water such as an ocean, sea, lake, or river have historically been a problem for marine vessels such as tankers, barges, and other ships. Accidents involving marine vessels historically include, but are not limited to, groundings, collisions, rammings, structural failures, and explosions. For vessels transporting cargo, if an opening or breach in a hull, tank, or other containment structure occurs as a result of an accident, the internal cargo is susceptible to accidental discharge from the vessel into the environment, especially if the cargo is a liquid such as oil. Discharge of a cargo such as oil into an environment such as an ocean or river often incurs costs such as from cleanup, fines, damage claims, cargo value losses, insurance rate increases, and public image losses. Preventing, reducing, or limiting the rate of the discharge of cargo into the environment averts or mitigates these costs.
In addition, damage sustained to vessels can have adverse effects on the stability of the vessel. Since the location and extent of the damage is often unknown at the time of an accident, the operator of the vessel cannot make well-informed decisions about the best strategy for removing his vessel from danger, or about the extent of the potential threat of accidental discharge of cargo. Often experienced divers must be transported to the site and enter the water to assess the damage, exposing themselves to a potentially dangerous situation.
Finally, holes in the hull of a vessel can result in an influx of water and may result in the sinking of the vessel. Various techniques have been used to keep a damaged vessel afloat, such as wrapping the sail of a ship around a breached hull to prevent water inflow.
Various devices are known for emergency repair of a ship to prevent it from sinking. U.S. Pat. No. 373,133 to Duncan, U.S. Pat. No. 1,070,260 to Jameson, U.S. Pat. No. 3,183,876 to Kronhaus, U.S. Pat. No. 3,400,684 to Gerardi, and U.S. Pat. No. 4,026,233 to Cox each disclose covers used to encase an opening in the hull of a marine vessel. These disclosed devices are designed to prevent water from entering the vessel.
A slightly different technique is disclosed in U.S. Pat. No. 1,573,909 to Blumberg which discloses the use of a mattress to cover a hole in the hull of a vessel. The mattress also includes a pipe or hose placed through the mattress for the purpose of pumping water out of the hole.
For vessels transporting cargo, numerous marine types of oil and hazardous chemical spill response equipment and techniques are presently in use to mitigate losses which occur as a result of accidental discharge of the cargo. Presently, with a few exceptions, marine oil and hazardous chemical spill response equipment and techniques generally focus on containing, recovering, or cleaning up a cargo spill rather than preventing cargo discharge. For example, conventional mechanical containment, recovery, and cleanup equipment includes booms, skimmers, oil/water separators, beach cleaning equipment, pumps, storage tanks, and sorbents. Conventional chemical containment and cleanup includes dispersants, gelling agents, and various other chemical agents. Other techniques such as in situ burning and bioremediation are also presently used in spill response as well. Numerous products pertaining to all of the above types of equipment and techniques can be found in the World Catalogue of Oil Spill Response Products published by Port City Press of Baltimore, Md. or the International Oil Spill Control Directory published by Cutter Information Corporation of Arlington, Mass.
Some present technologies, equipment, and techniques seek to prevent the accidental discharge of cargo. Double hulls, double bottoms, and double sides are different types of naval architecture which prevent spillage in some cases by providing an additional hull layer, wherein an outer hull layer absorbs much of the impact during an accident so that an inner hull layer is not breached and can contain the cargo. Internal pumping and cargo transfer mechanisms such as the SCOL by Energy Transportation Group, Inc. of New York, N.Y. have also been used to transfer the cargo in a damaged tank to an undamaged tank before all cargo is discharged.
Another technique involves the use of liners. Liners, a high-strength flexible membrane covering the inner wall of a tank, are intended to contain cargo when the hull is breached. Several practical obstacles exist with the use of liners, including their inability to conform to the intricate inner structure of most tank vessels and their hindrance of normal hull inspections. The National Research Council assessed the practical obstacles associated with liners and found the obstacles to be insurmountable.
Many patents have disclosed several inventions which seek to cover or close openings in the hull of a vessel, either to prevent the influx of water which may sink the vessel or to prevent the outflow of cargo.
U.S. Pat. No. 770,078 discloses a flexible curtain for covering openings in vessels with the curtain being unrolled along side the ship to cover a hole in the hull. Magnets on the curtain assist in securing it against the hull over the opening.
U.S. Pat. No. 932,720 discloses a means for closing holes in a steel hull in which a series of magnets may be activated for securing an inflatable bag or blanket to the hull. The blanket is made of a strong material, such as canvas and rubber combined, which is impervious to water or air.
U.S. Pat. No. 3,669,055 discloses an apparatus and method for sealing an opening in the hull of a vessel. The apparatus used to seal the opening is a cover which is secured to the hull. The cover is formed of an elastomeric material such as rubber and the outer layer has an armored surface to protect it from sharp, jagged edges which may form around the opening.
U.S. Pat. No. 3,756,294 to Rainey discloses an apparatus whereby an elongated conduit with an enlarged end is attached to the hull magnetically over an opening in the hull to guide the oil from its source of leakage to a large sack-like underwater container which contains the spilled oil.
U.S. Pat. No. 5,216,973 to Gwinn uses a large sheet of flexible, durable, waterproof material which is deployed around the vessel to form a double hull type apparatus. The material is deployed from port to starboard (or vice versa) from a roll in a protective housing on deck. The material is pulled around the hull mechanically. Although the cargo is contained within the material, it still exits the hull which can be seen as a disadvantage. Also, it requires a large amount of material to implement this technique. The operator is not informed as to the extent of the damage from the accident.
U.S. Pat. No. 5,203,273 to Sandlofer uses a large skin, preferably with a dehydrated material, which is rapidly deployed around an oil transportation ship to absorb any spilling oil and to plug the hole.
U.S. Pat. No. 5,009,180 to Holt uses a flexible waterproof sheet to encase a portion of the hull to prevent the outflow of oil from a tanker. The sheet is deployed from the deck and it wraps around the hull from one side to the other covering the opening.
U.S. Pat. No. 5,195,446 to Riddell uses a sheet of flexible, liquid impermeable material having numerous electromagnets embedded within the sheet. By controlling the sequence in which the electromagnets are energized, the sheet may be incrementally attached to the hull of a vessel to cover an opening. Fluid assist members adjacent to the electromagnets are used to force the sheet towards the hull, and a separate flotation device is described which can transport the sheet towards the hull of the vessel and unroll it in the water prior to application to the hull.
Magna-Patch of Houston, Tex. utilizes a concept similar to that described in the Riddell patent. Magna-Patch cannot locate and assess damage to the extent capable of with the present invention. Unlike the present invention, the Magna-Patch device cannot be used effectively with moving vessels. The Magna-Patch device is not as effective as the present invention in covering long openings in a hull which are oriented along the length of the vessel. The Magna-Patch method requires continuous power to keep the patch in position on the hull.
Very few commercial products currently on the market perform external hull patching, and none known to applicants locate and allow for hull damage assessment and repair as does the present invention.